Plant for the artificial drying of ceramic products and in particular of tiles and bricks



J. B. MONNIER Filed Jan. '7, 1956 mxxixxxwmf@ mvmrm Aug. l0, 193 7.

PLANT FOR THE ARTIFICIAL DRYING OF CERAMIC PRODUCTS AND IN PARTICULAR OF TILES AND BRICKS Patented Aug. 10, 193'?v UNTED STATES PATENT OFFICE Jean Baptiste Monnier, Gap, France Application January 7, 1936, Serial No. 57,988 In France January 17, 1935 2 Claims.

It is known that in actual drying processes use is made of tunnel dryers in which are introduced the products to be dried, placed on small wagons or cars provided with shelves and which are 5 caused to intermittently or continuously move in said tunnel at a speed proportional to the rapidity of drying it is desired to obtain. `This rapidity of drying is itself a function ci the speed of circulation of the air in the dryer, as well as of the l0 temperature andhygrometric condition of said air, which circulates in reverse direction to that of the displacement of the small wagons or cars.

Actually knowntunnel dryers allow of obtaining results which, in general, are satisfactory when ceramic products, and in particular tiles or bricks made of clay relatively porous or of normal shrinkage, are to be dried. In the case under consideration, the drying of the brick or tile requires about thirty-six hours. I'his is not so for products which, owing to their chemical composition or physical structure, have a small capillarity or a high shrinkage, this necessitating the slowing down of the drying in Yorder to avoid distortions and the production of cracks, particularly when tiles or bricks of large dimensions are being treated. In fact, cases are known in which the drying lasts from seventy to one hundred and twenty hours, cases in which the output of the articial dryers becomes so small that for obtaining an advantageous industrial production, it is necessary to use plants which are too large and, consequently, too costly. This is the reason Why it has not heretofore been possible to use some qualities of clay in the ceramic art and in particular in the manufacture of tiles.

The improvements forming the subject-matter of the present invention allow of remedying these inconveniences.

In fact, they allow of utilizing clays of small capillarity and high shrinkage and of materially reducing the time required for drying, without causing any distortion or crack in the dried products.

The improved process forming the subject-matter of the invention is based on the fact that it has been found that these distortions and cracks occur before the shrinkage of the clay is terminated, and once this shrinkage is terminated, it is possible, without inconvenience, to accelerate the drying operation for eliminating the quantity of Water (about 8%) still remaining in the treated products.

According to the invention, the drying of ceramic products, and in particular of bricks and tiles made of clay having a small capillarity and a high shrinkage, is effected in two phases. During the first phase, the products to be dried are exposed intermittently to the action of hot air in circulation, and as soon as the shrinkage is terminated, said products are subjected to a nal 5 intense drying, so as to eliminate the remainder of the moisture.

During the time the ventilation is stopped in the rst phase, the moisture within the products to be dried moves towards the surface and the ends of l0 said products, which moisture is subsequently removed when the ventilation is resumed, without production of cracks or distortions, which would inevitably happen if the ventilation was contin- Another object of thei-nvention is to provide an improved dryer for carrying out the process which has just been described. This dryer is constituted by a passageway comprising a plurality of and preferably two main tunnels, in which the first phase of drying by intermittent ventilation is effected.

These main tunnels are provided on either side of an auxiliary tunnel of smaller length arranged in the middle portion of the dryer and in which 25 the products removed from any oi the main tunnels after completion of shrinkage, are subjected to the nal intense drying constituting the second phase of the process. Said dryer is also characterized by the application of means allowing hot 30 air to be sent at will in either of the main tunnels and to reverse at the same time the direction of circulation of the heating fluid through the auX- iliary middle tunnel, through which said fluid always passes, in one direction or the other. 35

lIv'his result is obtained according to the invention by utilizing a system of associated valves controlled together and intermittently by any suitable mechanism, so that when one of the valves is in the open position, the other is in the 40 closed position, and vice versa.

A form of construction of the improved dryer according to the invention is diagrammaticaily illustrated, by way of example only, in the accompanying drawing. 45

As will be seen from the single figure of this drawing, the tunnel dryer, applicable in particular to the drying of bricks and tiles, comprises two main tunnels l and 2, having the same length, arranged in alignment with each other and each 50 adapted to receive a train of small wagons 3 provided with shelves, this train entering each of these tunnels through the corresponding door 4 or 5. Between these two main tunnels and in the middle portion of the dryer is provided an 55 tor S which is supplied with steam arising eitherl 55 one interval of time to the other.

from a suitable steam engine, or from a boiler (engine or boiler not shown inthe drawing), the outflow of this steam being controlled by1a cock or valve II.

the products are cooled, and it can also draw in hot air arising from a furnacev provided for that purpose.

'I'he dryer which has just been describedoperates as follows:

The air entering from the exterior through the opening 8 is set in motion by the fan l; it passes through the radiator 9, in which it is raised to the desired temperature by suitable adjustment of the passageway of the cock or valve II provided in the pipe line III.

In the position shown in full lines in the drawing, the valves I2 and I3 compel the ventilating air to pass through the tunnel 6 and, sublfsequently, through the tunnel I for returning,

through the return conduit I4, to the fan I from which it is again sent through radiator 9, tunnels 6 and I and return conduit I4, continuing the circuit in which it circulates during ve minutes, for

instance until the mechanism diagranfimaticalli7 shown at I6 and adaptedtosimultaneously control the valves I2 and I3, causes these latter to suddenly assume the position indicated in dotted lines. v

In these conditions, the ventilation of tunnel 'I is interrupted, and the heating-fluid is compelled to pass through tunnel 6 in reverse direction, for subsequently circulating through tunnel 2, from which it returns to the fan `through the other return conduit I5 which is in alignment with conduit I4.

After a further interval of ve minutes, the control mechanism IIS suddenly moves back valves I2 and I3 to their original position, that 5 0 is to say the circulation of the heating fluid is interrupted in tunnel 2, whilst it is reestablished in tunnel I and is reversed in tunnel. 6.. The latter is thus continuously ventilated; it isonly the direction of circulation which changesfrorn It is to beunderstood that said interval of time is. variable according to circumstances and according totl'ie-l Itis moreover to` naturev of the clay treated. Y K be understood that atmospheric air drawn in through the adjustable opening l8. canv also'lbe mixed in variable proportions with the damp air..l

circulating in the return circuits. According'to the working conditions of the plant, it is also possible, if it is considered necessary, to evacuate at I 'I or at ITI any required quantity ofjsaturated air.

As is previously indicated, when the products of a wagon placed at the inner end, offoneo'f the main tunnels have dried to complete shrinkage, said wagon is moved into the secondary middle tunnel (i where it is subjected to a second drying operation, that'is to say the nal intense drying.

In the form of construction i1lustrated,.it has This: fan can also draw int. l5 hot air recovered in the oven, in the Zone where.

been assumed that in the secondary tunnel Ii are simultaneously treated two Wagons subjected to the action of the heating uid alternately circulating in reverse directions, that is to say sometimes in the direction of the arrow I8 and sometimes in the direction of the arrow I8. y

The two'wagons placed in tunnel are rcmoved, by means of travelling platforms, through two side doors I9 and I 9 provided in the-'middle portion of the dryer. It is by means of the same travellingplatforms that a wagon isv removed from the main tunnels I and 2 for introducing it in the secondary tunnel 6.

'Ihe main tunnels I and 2 are then entered through their respective doors 4 or 5, and the entire train of wagons is pushed into each of these tunnels according `to a distance corresponding to the length of a Wagon. A wagon of products vto be dried is then introduced in each of the tunnels I and 2 and the doors 4 and 5 are closed.

As the temperature of the dryingl air is not, 'k

generally speaking, too high, it is unnecessary to stop the ventilation during the manipulation of the wagons.

In the dryer according to the invention, the Y drying very eiciently takes place since, whilst the products, inthe secondary tunnel, are subjected to a continuous and powerful drying during twoA hours, those treated inthe main tunnels are subjected to a slow drying duringV twenty hours, each of these main tunnels containing, in the example illustrated, ten wagons for two in the secondary tunnel.

It will also be noted that the process just described ensures a most methodical drying in the main tunnels,.the wagons being pushed in. a direction reverse to that of the circulation of the air, that is to say the products introduced in said tunnels are first brought in contact with air moistened owing to itsKA passage in there-V mainder of the Vtunnel and are progressively brought in contact with air less ,saturated with steam, inv proportion as the wagons move Io'r- Ward towards the middle lportion of' the dryer` which is in the immediate neighbourhoodof the',

source of heat.

What I claimis: 1. A plant for the articial drying of ceramic products by the passage of a heating fluid theref over, comprising a passageway including a plurality of main tunnels and anauxiliary relatively sliort tunnel interposedY between said main tunnels, means for heating the heating fluid,.

means for propelling the latter through said tunnels, and` means for intermittently reversing. the direction of ow of' said heating fluid throughsaid auxiliary tunnel andv for' causing the said uid to iiow intermittently through one main tunnel'or the other depending on the dir-V,

end tunnels being substantially longer than said auxiliary tunnel, and means for selectively ,cir-

culating saidheating fluid through said auxiliary tunnel in one direction and through one end tunnel or through said auxiliary tunnel in the other direction and through the other end A tunnel. v

JEAN BAPTISTE MC)l\Il\lIER 

